html, body {  
    height: 100%;
    width: 100%;
    overflow: hidden;
}
body {
    margin: 0;          
}
#app {
    position: fixed;
    height: 100vh;
    width: 100vw;
}
/* 菜单栏 */
.menu {
    position: absolute;
    bottom: 20px;
    left: 0;
    width: 200px;
    color: #fff;
    padding: 20px;
    box-sizing: border-box;
}
.menu li{
    list-style: none;
}
.menu a {
    display: block;
    margin-bottom: 10px;
    color: #fff;
    text-decoration: none;
}
.menu a:hover {
    color: #f00;
}
